Cod sursa(job #689787)

Utilizator al.mocanuAlexandru Mocanu al.mocanu Data 24 februarie 2012 20:37:45
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.35 kb
Raporteaza aceasta sursa 
#include <fstream>
using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

long N,i,j,k=0,v[1000001];

int main()
{f>>N;
for(i=1;i<=N;i++)
v[i]=i;

for(i=2;i<=N;i++)
{
    if(v[i]==i)
    {
        for(j=i;j<=N;j=j+i)
        v[j]=v[j]*(i-1)/i;
    }
}

for(i=2;i<=N;i++)
k=k+v[i];

g<<2*k+1;

return 0;
}